Yes, mostlikely imported via Warsaw or maybe Minsk...?
But, mind my saying Dad, kindly take a look at "Пробирный Устав от Февраля 1882 года"...Кроме остновных рассмотренных выше клейм, Инструкцией 1882 года вводиаисьдополительные: специалное клеймо для ПРИВОЗНЫХ ТОВАРОВ ... In other words as from 1882, not before.
This punch ПТ was the first Russian import mark. Before 1882 imported goods were brought by the customs to the Russian assay office in order to verify the lowest legal fineness of 84 zolotniki (875/1000) before the import. If the fineness was not less than 84, the import was granted and the assayer punched his hallmark on it. If not, the import was rejected. Therefore you can nowadays find such "Russian hallmarked" objects without a Russian maker's mark on the market sold as "Russian made", which they of course are not but imported from some other country, often Germany. This has been told many times in many threads through the years here. Use the search function and you will find more to read about Russian import and its marks.
In addition, before it became clear that this ПТ-mark actually was a Russian import mark, it was believed that ПТ was an unknown assayer's initials.